The Sixties are back with a vengeance. After Bond's Saved and Osborne's Inadmissible Evidence we now have an RSC revival of Peter Weiss's 1964 dialectical drama forever associated with the name of Peter Brook. But, while Anthony Neilson's new production has a lot going for it, it tends to submerge its insights under a somewhat strenuous sensationalism.

Neilson's most radical decision is to update the action. We are still watching a play within a play, supervised by the Marquis de Sade, about the death of Marat in 1793 and supposedly performed by inmates of the Charenton asylum in 1808.

But, while the structure is preserved, the physical aspects have changed. Marat is here a modern laptop revolutionary, Sade is a shape-shifting, cross-dressing spokesman for individualism and Charlotte Corday wears terrorist garb and kills Marat with a revolver rather than a knife. Even the asylum boss, who nervously presides over the event, controls the inmates by means of a smartphone.

Weiss's play is not holy writ and the updating has many beneficial effects. Marat's belief in equality and freedom from oppression chimes with a world of street protests against dictatorship and popular demonstrations against the banker's iniquities. Equally Sade's advocacy of untrammelled individualism has its echo in an erotically obsessed, narcissistic society enthralled by technology, celebrity and material goods. And, just as Weiss's play comes to no definite conclusion, so Neilson's production leaves us to decide which set of values should prevail.

My objection is to the overkill in the actual staging. Unable to leave well alone, Neilson bombards us with shock effects. When Sade, for instance, asks to be beaten while talking about revolution, what we see is a figure in silky lingerie being attacked by a stun-gun-wielding Charlotte Corday: infinitely less effective than the moment in the Brook production where Glenda Jackson whipped Patrick Magee with the strands of her hair.

And when the asylum inmates run riot at the end of the first half, Neilson spares us nothing including the sight of a naked Nicholas Day being gang-raped at the front of the stage. This, and much more, strikes me as Artaud for Artaud's sake rather than a clarification of the play's central ideas. The piece is performed with bravery and commitment by a large ensemble.

Jasper Britton, left, makes of the Marquis de Sade an egoist who contain multiple conflicting identities. Arsher Ali's Marat exudes the right martyred, ideological earnestness. And there is good work from Christopher Ettridge as the control-freakish asylum boss, Imogen Doel as the murderous Corday and Lisa Hammond, also shown left, as the Herald who narrates from a motorised wheelchair. Chahine Yavran's lighting, which at one point lends the whole theatre the undulating stripes of a Bridget Riley painting, is also outstanding.

There is much to admire in the production. I just wish it didn't attempt to overheat a play that is already warm enough in its fervent oppositional arguments.

• This article was amended on 24 October 2011. The original misspelled the name of the actor Imogen Doel as Imogen Joel, and referred to a Taser, which is a registered trademark, rather than a stun gun.